Bon Iver is on a hiatus though, and may never be back. Bands like Brand New have never gone on hiatus, they just release music infrequently.
He's talked about getting away from music, don't know if he actually is or not. I guess it depends on what you consider a "hiatus." I see Brand New not releasing music in the same way I see FOB being on a hiatus. Even though Brand New hasn't SAID they are on a hiatus, if FOB was to come back and release new material before them it seems kind of silly to use the word.